To improve the stability of output from electricity storage apparatuses, demand has recently increased for the installation of a plurality of electricity storage apparatuses in a consumer facility or the like. In the electricity storage system disclosed in patent literature (PTL) 1, a control apparatus monitors the state of charge (SOC) and the number of discharges of the storage cell in each electricity storage apparatus. The control apparatus in the electricity storage system disclosed in PTL 1 also performs control, in accordance with the state of each storage cell, to discharge the storage cells in order from the storage cell with the highest priority.